Goldbeater&#39;s lubricant



Patented fies. 25, E245 GOLDBEATERS LUBRICANT Donald D. Swift, Hartford, Conn, assignor to M. Swift & Sons, necticut Inc., a corporation of Con- No Drawing. Original application October 28,

1939, Serial No.

301,797, now Patent No.

2,354,072, dated July 18, 1944. Divided and this application July 18, 1944, Serial No. 545,541

3 Claims.

This application is a division of application Serial No. 301,797 filed October 28, 1939, Goldbeating lubricant, now Patent No. 2,3 4, 2. patented July 18, 1944.

My present invention relates to the goldbeaters art and more particularly to an improved lubricant to be used with goldbeaters skin.

In beating gold or other metallic leaf, it is customary to place small squares of gold in a packet, each square between sheets of cutch paper, the entire packet then being beaten until the gold or other metal spreads to the size of the enclosing sheets. The metal is then quartered used instead of the calcium sulphate. It is preferred that a uniform mixture be obtained so that the fine particles of the dehydrated calcium sulphate powder or soap are suspended in. the solution of the sodium stearate or sodium palmitate in alcohol, the alcohol tending to inhibit hydrolysis of the soap. The alcohol is then and the quarters are placed between packets of goldbeaters skin and further beaten. This process is continued until the leaf has reached the desired size and thinness.

The conventional goldbeaters skins are of 7 animal origin, but substitutes such as Cellophane or cellulose acetate may be used. To facilitate the beating operation, it is customary to "doctor" the goldbeater's skin or the substitute and to add a suitable lubricant. The conventional doctoring long used for this purpose consists essentially of isinglass, gum arabic, shellac, and spices such as saffron, cinnamon, and cloves in red wine. The lubricant is usually made up from soap, gypsum, and water, or in some instances, alcohol.

I have found that a greatly improved goldbeater's lubricant is obtained by the use of a mineral carrier which is soft enough to be scratched by a fingernail and which can be subdivided to almost microscopic dimensions. I

have found that the imbedding of such a mineral carrier in a fatty acid sodium salt produces a far superior lubricant.

To this end, I prepare the lubricant of the present invention by dissolving a fatty acid sodium salt such as sodium stearate or sodium palmitate in a suitable alcohol such as propyl alcohol; suitable organic soaps may be used in place of the sodium stearate or palmitate. Thedesired characteristics of the salt'are that it be soluble in alcohol, non-adhesive, with a fairly high melting point and chemically stable. A mineral carrier meeting the aforementioned requirements, such as completely dehydrated calcium sulphate, in powder form. is then mixed into the solution; an alkaline earth soap, such as calcium, magnesium or' zinc stearate, may be evaporated by any suitable, well-known method and the residue is a smooth, fine-grained lubricant far superior to any that have heretofore been used. 1

It is preferred to use such proportions of the sodium stearate or sodium palmitate and the completely dehydrated calcium sulphate that the final product comprises particles of calcium sulphate each covered with a surface layer of soap. For example, 6% oz. of sodium stearate are dissolved in about 3 qts. of alcohol. After the soap is completely dissolved, 12 lbs. of completely dehydrated calcium sulphate in a finely powdered form are slowly stirred into the solution. The alcohol is then evaporated.

will not scratch or puncture the gold or other metallic leaf during the beating operation and has very superior lubricating qualities.

While I have described a specific mineral carrier and specific soaps, it is obvious that other carriers and other soaps or their equivalents may be used in varying proportions, without departing from the spirit and the scope of the invention as defined in the appended claims.

I claim:

1. The method of preparing a lubricant for metal beating, comprising the steps of dissolving sodium stearate in alcohol, mixing com pletely dehydrated calcium sulphate uniformly therein to obtain a suspension of the calcium sulphate in the sodium stearate solution; and

evaporating the alcohol.

2. An improved lubricant for metal beating comprising. comminuted particles of dehydrated calcium sulphate, each particle being covered by a'surface layer of a fatty acid sodium salt soluble in alcohol, non-adhesive, having a fairly high melting point, and chemically stable.

3. An improved lubricant for metal beating comprising comminuted particles of dehydrated calcium sulphate,'each particle being covered by a surface layer ofsodium stearate.

. DONALD D. SWIFT.

The resultant lubricant is fine grained, soft, I 

